For large scale storage, transportation and dispensing of flowable materials such as liquids and pulverulent solid bulk materials, as well as of gases, it is known to provide a container assembly which comprises an outer supporting container and a plastic foil or film liner which can originally be in a flaccid condition and can be expanded by the introduction of the flowable materials into this bladder.
The outer container can have a pipe fitting to which a cover or valve or cock is connected and the bladder may have a tubular portion which can extend through this fitting and can be applied to an outer edge thereof to provide communication from the interior of the bladder to the exterior of the container.
The container can have an opening at the upper end through which the bladder can be inserted and filled if desired. The opening in turn can be closed by a cover.
In general, such container assemblies are intended to hold relatively large volumes. For example, the capacity of such a container can be 1000 liters or more (see German Patent Document DE-GM 88 07 118). The foil bladder allows the outer container to be reused without the need to clean the outer container simply by replacement of the bladder. The bladder can be disposable. For example, the material contained in the bladder may be an environmentally hazardous method and any residues can remain in the bladder for disposable and the outer container can be reused by the insertion of a new foil or film bladder.
In such cases it is not necessary to engage in expensive or time-consuming procedures to clean the interior of the outer container or to decontaminate it. It will be self-understood for such purposes that the foil bladder which must receive the liquid or pulverulent flowable material, should not be penetrable or easily damaged. In fact, when the foil bladder is filled, it is already within the outer container and thus fully supported.
In the container assembly described in German Patent Document DE-OS 22 55 299, the outer container is a barrel or drum. The inner container is provided as a bag which is inserted into the drum and is connected to the bung in the barrel top. Problems are encountered with such systems when the wall of the inserted bag is not connected with the inner wall of the barrel.
There is a danger that the bag will tear away from the bung opening and discharge its contents into the interior of the barrel.
In a system of another type, a folded container has a throughgoing opening for the outlet tube of an inner bag (see German Patent Document DE-AS 12 78 335). In this case, the inner bag has an outlet fitting which is arranged at an upper portion of the folded container and passes through the throughgoing opening of the latter at this upper region. It can also be jammed and torn.
With the container assemblies which have been described there is the further problem that the foil bladder does not always lie smoothly along the inner wall of the outer container but can form uncontrollable folds which lie against the inner wall of the outer vessel and are locked in place under the pressure of the filling material. This can result in stress upon the foil bladder which, in conjunction with vibrations and oscillations of the mass within the assembly during transport by road, rail or ship, give rise to leaks.